What types of imaging tests are used for children?
X-rays
During an x-ray, electromagnetic waves (a form of light) pass through the body and create an image on film.
Time: Each x-ray takes only a few seconds, like a picture taken with a camera.
Radiation: X-rays expose the body to very small amounts of radiation, but only to the areas of the body being studied.
Pain: None.
Before the test: Nothing special needs to be done before the test.
During the test: The body part to be examined is placed between the x-ray machine and the x-ray film. Other parts of the body may be covered with a lead-lined apron to reduce radiation exposure. The machine is turned on, and a picture is taken. Patients must keep very still for the image to be clear. Young children may need special straps to keep them still during the test.
Fluoroscopy
Fluoroscopy is a type of x-ray that creates a real-time "x-ray movie" of the inside of the body. An x-ray beam placed on a specific area of the body creates images that are shown on a TV-like monitor.
Time: About 5 to 20 minutes.
Radiation: Higher than x-rays, but it depends on how long the test lasts.
Pain: None, but preparing before the test may be unpleasant.
Before the test: For some types of fluoroscopy tests patients may need to fast, drink only liquids, or have an enema. Sometimes a contrast material (a fluid that shows things in the body that are hard to see without it) is injected or given by mouth. If the child cannot drink it, a tube may need to be placed through the mouth to the stomach.
During the test: The room is darkened, and the area of the body being examined is placed between the x-ray and fluoroscopy screen. Images of the body are then sent to a monitor where they can be seen in motion.
Computed Tomography or CT scan
A CT scan is a special type of x-ray that uses computers to create detailed images of the body.
Time: A CT scan only takes a few seconds.
Radiation: Higher than x-rays but lower than the dose from fluoroscopy.
Pain: None, unless the child will need an injection of a contrast material. This must be done through a vein (IV) in the arm.
Before the test: A contrast material may need to be injected or taken by mouth.
During the test: The patient lies on a narrow table that slides in and out of the CT scanner. The x-ray tube rotates around the patient, sending information to a computer that forms the images.
Magnetic Resonance Imaging (MR imaging or MRI)
An MRI uses a large and powerful magnet, radio waves, and a computer to create very detailed images of the inside of the body.
Time: About 30 to 60 minutes.
Radiation: None.
Pain: None, but patients may need an injection of a contrast material and an IV. Also, some patients may feel cramped in the machine (open MRI machines are available in some areas). During scanning, loud humming and knocking will be heard. Small children may be frightened by these noises.
Before the test: Younger children may need to be sedated before the test.
During the test: The patient lies on a table that slides into the scanner (a narrow tunnel that holds the magnet). Inside the scanner, the patient will hear a fan and feel air blowing. Because the machine can be noisy, patients are given earphones. Some centers have headphones that your child can use to listen to music during the exam.
Ultrasound (Sonography)
Ultrasound uses sound waves to create images of the body. The sound waves enter the body, and the returning echoes are captured as images.
Time: 15 minutes to 1 hour.
Radiation: None.
Pain: None.
Before the test: In some cases, patients may need to fast or drink more water before the test.
During the test: First, a special jelly or oil is put on the skin. Next, a hand-held device called a transducer is moved back and forth over the area being examined. The transducer creates sound waves (that can't be heard or felt) that are reflected back to the machine. A computer creates images from the sound waves.
Nuclear Imaging
A nuclear imaging scan (sometimes called radionuclide scanning) shows the structure of a body part as well as how it works. Before the scan, a radioactive substance called a tracer is injected or given by mouth. A machine called a gamma camera used outside the body then detects the rays of energy given off by the tracer, and an image is created and shown on a computer screen.
Time: Between 15 minutes and 1 hour.
Radiation: Less radiation than from fluoroscopy or CT. The tracer loses its radioactivity within 24 hours, leaving the body in the urine or stool.
Pain: None, but patients may need the tracer injected and an IV.
Before the test: The tracer is usually given by mouth or through an injection. Patients may need to fast or drink a lot of water before some nuclear imaging scans.
During the test: After the tracer is in place, the patient lies on a scanning table. The camera is then moved slowly over the body. Images are created and displayed on a computer.
